{
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\begin{tabular}{l*{2}{c}}
\hline\hline
                    &\multicolumn{1}{c}{\specialcell{\;\;\;\;\; Arsenic \\ contamination \\ \;\;\;\;\;(WHO)}}&\multicolumn{1}{c}{\specialcell{\;\;\;\;\;\; Fecal \\ contamination}}\\\cmidrule(lr){2-2}\cmidrule(lr){3-3}
                    &\multicolumn{1}{c}{(1)}   &\multicolumn{1}{c}{(2)}   \\
\hline
Very poor x treated &      -0.064   &       0.043   \\
                    &     (0.084)   &     (0.084)   \\
Poor x treated      &      -0.030   &      -0.014   \\
                    &     (0.037)   &     (0.033)   \\
Low income x treated&      -0.032   &      -0.003   \\
                    &     (0.029)   &     (0.029)   \\
Middle income x treated&       0.009   &       0.006   \\
                    &     (0.031)   &     (0.028)   \\
High income x treated&      -0.106   &       0.146   \\
                    &     (0.108)   &     (0.107)   \\
\hline
R2                  &        0.06   &        0.04   \\
Obs                 &        6051   &        6051   \\
\hline\hline
\end{tabular}
}
